This invention relates in general to data transfer systems and more specifically to an apparatus and method for avoiding jitter and variations in payload size for a voice over packet network.
Traditional voice networks are based on 64 kbit/s synchronous transfer mode channels. Recently, new methods utilizing packet-based networks have emerged for transmitting voice. Carrying voice over a packet-based network introduces a number of problems such as jitter, various payload sizes, and lack of unified Quality of Service.
The usual method for transmitting G.711 (64 kbit/s) based payloads across a packet based network, such as an Internet Protocol (IP) network, is via compression technology (e.g. G.723/G.729) in order to optimize bandwidth utilization over the Internet. Some prior art methods address the problem of variable payloads by using de-jitter buffers, however, most of these methods are based on single voice channel streaming. One such product is the NetMeeting(trademark) application by Microsoft Corporation.
According to the present invention, a system is provided for carrying G.711 (64 kbit/s) based voice payloads across a packet-based network while overcoming the problems of network jitter and variable payload size.
More particularly, two concurrent tasks are implemented according to the invention, as follows: a Voice Packet Processing task and a Voice Packet Forwarding task. The Voice Packet Processing task receives packetized voice from a packet oriented interface, processes headers of the packet, and builds a payload buffer that is managed as described in greater detail below. The Voice Packet Forwarding task builds a payload buffer from the G.711 voice samples received from the synchronous interface, builds the necessary protocol headers and forwards the packet to the packet oriented interface.